Instrument Cluster Description and Operation: Speedometer
WARNING: This page is about a different car, the 2008 Pontiac G5 and 2008 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
The instrument panel cluster (IPC) displays the vehicle speed based on serial data message from the body control module (BCM). The BCM receives vehicle speed data from the PCM/ECM via the serial data circuit. The speedometer will default to 0 km/h (0 mph) if:
- The PCM/ECM detects a malfunction in the vehicle speed sensor circuit.
- The BCM detects a loss of serial data communications with the PCM/ECM.
- The IPC detects a loss of serial data communications with the BCM.